A 23-year-old man comes to the office due to a genital lesion. Two weeks ago, he noticed a small bump on the shaft of his penis that grew before ulcerating. The lesion is nonpainful, and the patient has had no fever or other skin lesions. He has never had similar symptoms. The patient has no chronic medical conditions. He recently began a new sexual relationship, and his use of condoms has been inconsistent. Vital signs are within normal limits. Genital examination shows a 2-cm ulcer on the midshaft of the penis with raised, indurated margins and a smooth base. Palpation does not elicit pain, and no exudate is present. No additional skin lesions are found, and oral examination is normal. Mild, bilateral, nontender inguinal lymphadenopathy is present. Testing for serum VDRL and HIV is negative. Which of the following is most likely to yield a diagnosis in this patient?

Question

A 23-year-old man comes to the office due to a genital lesion.  Two weeks ago, he noticed a small bump on the shaft of his penis that grew before ulcerating.  The lesion is nonpainful, and the patient has had no fever or other skin lesions.  He has never had similar symptoms.  The patient has no chronic medical conditions.  He recently began a new sexual relationship, and his use of condoms has been inconsistent.  Vital signs are within normal limits.  Genital examination shows a 2-cm ulcer on the midshaft of the penis with raised, indurated margins and a smooth base.  Palpation does not elicit pain, and no exudate is present.  No additional skin lesions are found, and oral examination is normal.  Mild, bilateral, nontender inguinal lymphadenopathy is present.  Testing for serum VDRL and HIV is negative.  Which of the following is most likely to yield a diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d46d_b8ff_bc81_c790c79287cd_MD0003_00 This patient with a new sexual partner developed a single, nonpainful penile ulcer with indurated borders and a clean base, raising strong suspicion for primary syphilis (chancre). Chancres typically arise ~3 weeks after inoculation and last 4-6 weeks in the absence of treatment. The diagnosis of syphilis is generally made using 2 categories of serologic tests: Nontreponemal testing (eg, VDRL) is quantitative (eg, titers) and identifies the reactivity of infected serum to cardiolipin-cholesterol-lecithin antigen; it is not specific for treponemal antigens. Treponemal testing (eg, fluorescent treponemal antibody absorption [FTA-ABS]) is qualitative (either positive or negative) and identifies antibodies to specific treponemal antigens. Although either category of test may be used to screen for syphilis, nontreponemal testing has higher false-negative rates (20%-30%) in patients with primary syphilis, particularly early in the disease course. FTA-ABS has the highest diagnostic sensitivity (>97%) in patients with early primary syphilis and can be used to establish the diagnosis in patients with negative initial VDRL results when there is a high suspicion for syphilis (as in this patient with a chancre). Darkfield microscopy, which directly visualizes treponemal organisms in exudates, is no longer commonly used because it is not routinely available. (Choice B) Herpes simplex PCR can diagnose genital herpes. However, herpetic lesions are generally painful (not painless) and are usually marked by multiple vesicles or ulcers on an erythematous base. In addition, systemic flu-like symptoms also frequently occur with primary infection. (Choices C and E) Lymph node aspiration and ulcer biopsy are not useful in the diagnosis of syphilis because Treponema pallidum cannot be cultured. (Choice D) A pathergy test diagnoses Behçet syndrome; it involves obliquely inserting a 20-gauge needle into the skin and checking the site 24-48 hours later for the development of a >2-mm papule. Behçet syndrome can cause recurrent genital ulcers but they are usually small, painful, and on the scrotum. Oral ulcers are also frequently present. Educational objective: Primary syphilis (chancre) is marked by a painless genital ulcer with indurated borders and a clean base. The diagnosis is made with a combination of nontreponemal and treponemal serologic testing. Treponemal tests (eg, fluorescent treponemal antibody absorption) have higher sensitivity (>97%) in patients with primary syphilis, particularly early in the disease course.

A 23-Year-Old Man Comes to the Office Due to a Genital